Antennas of the existing notebook computers are built-in the computers. Because a computer casing will not obstruct antennas, the operation of the antennas will be not affected. However, for waterproof, dustproof and shockproof notebook computers, high air-tightness and barrier property are required; as a result, antennas built-in the computers will be obstructed, thereby affecting the reception performance of the antennas and the normal operation of the computers. With the increasing requirements on performance, a plurality of expansion cards, such as video cards and memory banks, will be disposed in a computer. For portable computers, as the computers will be moved or transported due to job demands, and certain shock will be generated during the movement or transportation, the expansion cards will become loose or even fall off. In this case, the next time of use of the computers will be affected, and it is inconvenient for work. There is no extra available space for the existing computers, so it is difficult to additionally provide other auxiliary hardware, such as hard disks or expansion interfaces.